/Engine/Plugins/Animation/ControlRig/Source/ControlRig/Public/Rigs/RigHierarchy.h
Returns the MetadataChanged event, which can be used to track metadata changes Note: This notification has a very high volume - so the consequences of subscribing to it may cause performance slowdowns.
[FRigHierarchyMetadataChangedDelegate](API\Plugins\ControlRig\Rigs\FRigHierarchyMetadataChangedDele-) & OnMetadataChanged()